Centrifugal-pump balancing means



R. A. PITMAN.

CENTRIFUGAL PUMP BALANCING MEANS. APPLICATION FILED MAR. Ie. 1920.

1,360,576, 4 Patented Nov. 30,1920.

2 SHEETS-SHEET l.

R. A. PITMAN. CEN'TRIFUGAL PUMP BALANCING MEANS.

APPLICATION FILED MAR. I8. 1920. 1,360,576.` l Patented Nov. 30, 192i).`

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\ ober-ZPllnan/ UNITED STATES PAJTENToFFIcE- ROBERT`A. PITMAN, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR TO EARLE & MACHINE COMPANY, A CORPORATION OF PENNSYLVANIA.

GEAR

.CENTRIFU'GAL-PUMP BALANCING MEANS.

nppncationmea March 18,192.0. serial No, 366,852; i

To all whom t may concern:

Be it known that I, ROBERT A. PrrMAN, a citizen of the United States, residing in the city of Philadelphia,;county of Philadelphia, and State of Pennsylvania, have invented certain Centrifugal-Pump LBalanc ing Means, of which the following is a specilication.

This invention relates especially to `centrifugal pumps or water turbines having impellers of side or single suction type whether involving one'or several stages and its primary object is to provide means for automatically balancing such impellers.

This object is attained by` using sealing rings at the back of the impeller of diameters substantially larger than those of sealingrings at the frontor eye Vof the impeller; making the back sealing rings of such form that any movement of the impeller forward or toward the suction side will decrease the clearance between they fixed and movable rings and vice versa. v

The sealing rings-at the back are made substantially larger than those at the front 'or eye of the impeller in order that theV areas of the impellers sides, outside of the 4periphery of the rings, shall be unequal,

thev larger area being on the front or suction side. Inasmuch as these areas outsideV the rings are subject to approximately the discharge pressure of the impeller, there will be a tendency of the impeller due thereto to move rearwardly thereby increasing the clearance and leakage through the rings.

In addition to the sealing rings, one or more holes areprovided in the back of the impeller for connecting'the interior thereof with the exterior lying within the back sealing rings, the openings being forthe purpose-of allowing the leakage between these sealing rings to findits way back tothe suction side and equalize the pressure.

ing hole or holes in the impellerwhen the latter is'moved backward,which movement `hand a movement of the impeller in the opposite direction will reduce the clearance Specification of Letters Patent'. Patented NOV. 30, v1920 l l and leakage between these rings and open or K further open the hole or holes, therebyprothe axis of a two stage centrifugal 'pump provided with improvements; Fig. 2 1s a sectional view taken on the line QX-QX of Fig. 1, and Fig. 3 isa broken sectional l view taken through the axis of a *singlew stage centrifugal pump embodyingpa modi` fied form ofthe improvements.

As villustrated in Figs. l and 2, the pump comprises a base l which carries a twin' shell or case 2 provided with bearings?) having the shaft 4 journaled therein. y p

Impellers are xedjon the'shaftv and revolve within respective chambers of the case'.V Each impeller is provided at its forward or suction side with a hub 7 havingA Y, screwed thereon a bearing ring 8 `with stepped peripheral surfaces concentric with the shaft,th`e steps tapering from thehub, and reach impeller is provided at its rear side ,with a hub 9k havingscrewedthereon A a bearing ring 10 of larger diameter than thering v8) with stepped peripheral surfaces concentric with they shaft, the steps tapering toward the hub. Bearing rings l1 and 12, fixed Lin the case on opposite sides ofthe respective impellers, have stepped internal surfaces'conforming to the p n surfaces of the respectlve rlngs 8 and 10. I

Each impeller 5` is provided with yone orv space orchamber 15 in the case to the rear lof the impeller.` Each chamber 15 contains a circular bearing member 16 in the form of'y `more passages '13 opposite to its eyev or in-f.Y llet ltyand connecting itsv interior withf a a steppedcone or flanged tube against which s,

the impeller is adapted to move and close n y `the passage or passages 13.. v Means are provided for closing the equaliz- In operation, water' iiowing throughthe passage 17 enters the first kimpeller 5 A y through its eye'll and is discharged therefrom through the passage 18 tothe eye 14 of".y

the second impeller 5, `.being discharged from this impeller through the passage 19. v The impulse communicated by 'f the incoming water to each of the impellers ymoves it axially therewith and opens a space between the rings and 12, simultaneously closing the passage or passages 13 by moving the same against the member 16. The water which has been admitted to the chambers 6 and 15, back of the impeller, now acts upon a larger surface thereof and exerts a greater pressure thereon than the water acting on the opposite or front exterior surface of the impeller, which is thereby moved in the opposite or backward direction so that the passage or passages 13 are withdrawn from the member 16 and uncovered, thus relieving the pressure back of the impeller. The desired condition of balance or. equilibrium is thus attained.

In lthe modified construction shown in Fig. 3, a case `or shell 20is provided with the bearings 21 in which is journaled a shaft 22 having a single impeller 23 fixed thereon and revoluble in the chamber 24. The impeller is provided with a hub 25 projecting from its front side and having screwed thereon a ring 26 which is journaled in a bearing ring 27 set in the case. A hub 28 on the rear of the impeller has screwed thereon a ring or plate 29 of larger diameter than the ring 26, having a stepped conical periphery which expands outwardly and is journaled in a similarly stepped bearing ring 30 set in the case. The inner art of the ring 29 is adapted to be lapped y a flanged collar or member 31 fixed to the case so as to close the passage 'throu gli the ring between the spaces or chambers 32 and 33 on,k opposite sides thereof, the space 32 communicating through the passage or passages 34; in the back of the impeller with the interior thereof and the space 33 communicating through the space between the separated rings 29 and 30 with the chamber 24: in which the periphery of the impeller revolves.

In operation, the water flows through the passages 35 in the case 20 and vthrough the'A eye or inlet 36 ofthe impeller, whence it discharges through the kcasing passage 37 .having the chamber 2a in communication therewith.

Initially the impeller is movedrearwardly l so that the ring 29 is separated from the ring 30 and engages the ring or flange 31. Tater now leaks from the chamber 21lbetweenthe rings 29 and 30 to the chamber 33, with'the result that the total pressure now acting on the rear surfaces of the impeller is greater than that acting on the front surfaces and the impeller is moved in the reverse directie nV along its axis. The ring 29 being thereby withdrawn from the ring 31, thepressure in theV chamber 33 is relieved by water flowing therefrom through thelring 29 to the chamber 32 and thence through the passages 34 to theinterior ofthe impeller. Thus equilibrium and the balancing of the impeller are attained- Having described my invention, I claim:

1. In a centrifugal pump, the combination of a shell provided with an impeller chamber, of an impeller having an inlet in its front side and a passage in its rear side joui'- naled in said shell and revoluble in said chamber, and mechanism for balancing said impeller, said mechanism comprising a stationary ycircular bearin in said shell at the front side of said impe ler, a stationary circular bearing of larger diameter in said shell at the rear of said impeller, bearings iixed to said'impeller and adapted to coact with the respective bearings aforesaid, the coacting bearings at the rear of said impeller adapted to open and close a` passage between them when said impeller is moved axially in opposite directions, and means wherebythe open passage between said bearings last named is cut oif from said named.

2. In acentrifugal pump, a shell containpassage first ing an impeller chamber with Huid supply and discharge passages,an impeller of the side suction type journaled in said shell'and revoluble in said chamber, and means for balancing said impeller, said means comprising sealing members of different diameters at the back of said impeller so arranged that the rearward movement of the impeller opens ,the seal of largerv and closes the seal of smaller diameter, and the reverse movement of the impeller'closes the seal of larger diameter and opens the steal of smaller diameter.

3. In a vcentrifugal pump, a shell provided with aii impeller 'chamber having fluid supply and discharge passages, an

-impeller of the side suction type journaled in said shell and revoluble in said chamber, and means for balancing said impeller, said means comprising coacting surfaces Vdin said chamber at the opposite side of diameter is opened and of larger diameter is 1 closed when the impeller moves oppositelyh 4. In 'a centrifugal pump, a shell containing an impeller chamber with fluid supply and discharge passages, an impeller having an inletin a side thereof journaledl in' said shellfand revoluble in said vchamber, sealing means comprising a ring on the inlet side of said impeller land sealing means comprising a ring of larger diameter and a bearing on the opposite side of Vsaid impeller, said sealing ring -second named having a periphery. expanding from said impeller, and saidbearing havinga coacting similarlyA expanding interior.

InaV centrifugal pump, a shell containing an impeller chamber with Huid discharge and supply passages, an impeller with an inlet in a side thereof journaled in said shell and revoluble in said chamber,

sealing means comprising a ring and abearin'g on the inlet side of said impeller, and sealing means Comprising a bearlng and ring of larger d1ameters on the opposite side of said impeller, said bearing and ring second named having coacting stepped surfaces expanding from said impeller.

In testimony whereof, I have hereunto set my name this 15th day of March, 1920.

ROBERT A. PITMAN. 

